{"id":1975,"date":"2010-07-13T17:03:56","date_gmt":"2010-07-13T21:03:56","guid":{"rendered":"https:\/\/wpmu2.mit.local\/?p=1975"},"modified":"2010-07-13T17:03:56","modified_gmt":"2010-07-13T21:03:56","slug":"cnt-enabled-field-ionization-arrays-for-portable-vacuum-sources","status":"publish","type":"post","link":"https:\/\/wpmu2.mit.local\/cnt-enabled-field-ionization-arrays-for-portable-vacuum-sources\/","title":{"rendered":"CNT-enabled Field-ionization Arrays for Portable Vacuum Sources"},"content":{"rendered":"
\"Figure<\/a>

Figure 1: A proposed design of a field-ionizer unit consisting of an isolated vertical CNT and a high-transparency gate with electric field created between them.<\/p><\/div>\n

Micro vacuum-pump technology, which refers to vacuum-pump systems with miniaturized functional parts, currently attracts a noticeable interest from researchers due to the potential cost savings and energy consumption reduction that they would introduce [1<\/a>]<\/sup> [2<\/a>]<\/sup> [3<\/a>]<\/sup> [4<\/a>]<\/sup>, which would enable portability of many devices that require less-than-atmospheric pressure to operate.\u00a0 In this project we propose a MEMS\/NEMS field-ionization micropump that is able to operate at pressures as high as 30 torr and evacuate small (1 mm3<\/sup>) volumes to reach an mtorr-level vacuum.\u00a0 The field-ionization micropump can be integrated with other MEMS\/NEMS subsystems to span a pressure range between atmospheric pressure and high vacuum (10-6<\/sup> torr) to satisfy a wide range of applications that require portable vacuum sources.\u00a0 The field-ionization pump employs arrays of isolated vertically aligned carbon nanotubes (VA-CNTs) that have a proximal gate to generate local high-electric fields (108<\/sup> V\/cm) with low voltage, continuously ionizing gas molecules by field ionization. Positive gas ions then are attracted and implanted into the cathode getter, which is typically biased at 1kV.<\/p>\n

\"Figure<\/a>

Figure 2: Vertical CNT arrays on silicon columns with 5-um pitch. Catalyst nanodots used for isolated CNT synthesis were defined by the photolithography method.<\/p><\/div>\n

Our field-ionization pump consists of three major parts: an anode field-ionization array (i.e, the field ionizer), a cathode getter, and a gas inlet\/outlet. The schematic diagram of the field-ionizer unit is shown in Figure 1. The fabrication of the field-ionization pump involves the synthesis of isolated VA-CNT arrays at the wafer level. Instead of using low-throughput methods such as e-beam lithography to define the catalyst pads for VA-CNT growth, we have developed a technique that uses projection photo-lithography, which increases the fabrication throughput by four orders of magnitude. Figure 2 is a high-resolution SEM picture of an array of isolated VA-CNTs defined by the projection photo-lithography technique. Simulations of the pump predict an ultra fast air-extracting rate (3 seconds) for a 56-mm3 <\/sup>volume from ionization arrays consisting of 1 million isolated VA-CNTs, while the pump consumes less than 1W. [5<\/a>]<\/sup><\/p>\n

\r\nReferences
  1. N. Nguyen, X. Huang, and t. Chuan, \u201cMEMS-Micropumps: A Review,\u201d ASME J. Fluids Eng.,<\/em> vol. 124, pp. 384\u2013392, 2002. [↩<\/a>]<\/li>
  2. P. Woias, \u201cMicropumps\u2014Summarizing the First Two Decades,\u201d Proc. SPIE<\/em>, vol. 4560, pp. 39\u201352, 2001. [↩<\/a>]<\/li>
  3. D. Laser and J. Santiago, \u201cA Review of Micropumps,\u201d J. Micromech. Microeng.<\/em>, vol. 14, pp. R35\u2013R64, 2004. [↩<\/a>]<\/li>
  4. S. Shoji and M. Esahi, \u201cMicro Flow Devices,\u201d IEEE Fifth International Symposium on Micro Machine and Human Science<\/em>, pp. 89\u201395, 1994. [↩<\/a>]<\/li>
  5. J. Hauschild, E. Wapelhorst, and J. Mueller, \u201cA Fully Integrated Plasma Electron Source for Micro Mass Spectrometers,\u201d in Ninth International Conference on Miniaturized Systems for Chemistry and Life Sciences<\/em>, pp. 476\u2013478, 2005. [↩<\/a>]<\/li><\/ol><\/div>","protected":false},"excerpt":{"rendered":"

    Micro vacuum-pump technology, which refers to vacuum-pump systems with miniaturized functional parts, currently attracts a noticeable interest from researchers due…<\/p>\n<\/div>","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[11],"tags":[4064,71,4214],"_links":{"self":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1975"}],"collection":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/comments?post=1975"}],"version-history":[{"count":2,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1975\/revisions"}],"predecessor-version":[{"id":1979,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1975\/revisions\/1979"}],"wp:attachment":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/media?parent=1975"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/categories?post=1975"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/tags?post=1975"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}